Siemens SINUMERIK 840D sl Function Manual page 41

DB31, ... DBX1.3 (axis/spindle disable)
Stationary axis
If the interface signal is set for a stationary axis, all travel request are ignored as of this time.
The travel requests are retained. If the axis disable is cancelled when a traversing request is
pending DB31, ... DBX1.3 = 0 the motion is carried out.
Traversing axis
If the interface signal is set for a traversing axis, the axis is stopped using the currently active
brake characteristic. If the interface signal is reset while the travel request is still present,
traversing is continued.
Spindle
● Open-loop control mode: Speed setpoint zero is output immediately
● Positioning mode: See "Stationary axis" / "Traversing axis" above
DB31, ... DBX1.4 (follow-up mode)
The interface signal is only effective with the DB31, ... DBX2.1 (controller enable) interface
signal
DB31, ... DBX2.1
Follow-up
In follow-up mode, the set position of the machine axis is continuously corrected to the actual
position (set position = actual position).
Feedback: DB31, ... DBX61.3 == 1 (follow-up active)
During follow-up mode, clamping or standstill monitoring are not active.
Note
If the DB31, ... DBX2.1 (controller enable) interface signal is set during follow-up mode,
repositioning to the last programmed position is performed with REPOSA (approach on a
straight line with all axes) when the NC program is active. In all other cases, all subsequent
motions start at the actual position.
Hold
In "Hold" mode, the set position of the machine axis does not follow the actual position. If the
machine axis is moved away from the set position, the difference between the set position and
the actual position increases constantly (following error). The following error is suddenly
corrected if the controller enable is set without complying with the axial acceleration
characteristic (speed jump).
Feedback: DB31, ... DBX61.3 == 0 (follow-up active)
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
DB31, ... DBX1.4
1 Ineffective
0 1
0 0
A2: Various NC/PLC interface signals and functions
2.2 NC/PLC interface signals - only 840D sl
Operating mode
In closed-loop control
Follow-up
Hold
41